The attempt to present an overall presentation of Calvin's theological work has not been undertaken since the first half of the 20th century. The jubilee year 2009 has a wealth of excellent individual studies and compilations, particularly in the field of biographical and historical, and in some cases also systematic research But the interests of older research could not be satisfied with this. At that time one asked: Is there a "" middle "", a kind of center of gravity of his theology, comparable to the doctrine of justification in Lutheranism, around which the themes and perspectives of his theology could be grouped? This cannot be said of the doctrine of the sacrament. The search for a "" Central-dogma "" (Alexander Schweizer), a kind of "" material principle "", has also proven to be a mistake. The conclusion is that even the question of such a unifying principle or key could be posed incorrectly, and in any case cannot be answered by specifying a content-related element or problem of its theology. In any case, Calvin should no longer be measured by this expectation. One stands on much safer ground if one adheres, even when asking systematically, to the organizational aspects of the institute that emerged from his exegetical work. There is twice a pointed mention of the knowledge of God (from nature and from Scripture), then of the subjective appropriation of this knowledge in Christian life and finally, as it were as a point of convergence of the whole, of the scriptural constitution of the church, which is the place of the Proof of those insights should be. From this point of view and in relation to it, the problem of knowledge - specifically: the most precise possible text interpretation - is at the center of the present work. Knowledge does not mean the theoretical behavior of the modern viewer, but presupposes their involvement, their "" playing along "", i.e. their responsible participation in creation, in the process of reconciliation and in the path of the Church. Because the biblical prerequisite that he, the human being, has to deal with the living God in every situation and is set on the path by him, is the real lifeblood of the Calvinist sub- right.